1. Field of the Invention
The present invention relates to a gravity or pressure filter assembly that includes an underdrain block and a bed of granular filter media. More particularly, the present invention relates to a filter assembly that includes a clog resistant media retainer assembly for retaining the filter media on the underdrain block and preventing the build-up of biological and chemical scaling on the retainer assembly.
2. Description of Related Art
Typical gravity or pressure filters use some type of filter media that captures the dirt particles from a liquid being filtered as the liquid passes through the media to an underdrain or collection system. The filter media must be supported so that it will not pass into the underdrain or collection system.
One type of common media support utilizes one or more layers of gravel placed below the filter media to prevent the filter media from passing. Common gravel-less systems use either a slot sized small enough to retain the required media or plastic beads held together chemically or sintered together. Such systems are prone to clogging by biological or chemical scaling, which adheres to the media retainer, thus blocking or clogging the water pathway. The pressure drop across the filter assembly may continue to increase and cause a failure in the system when the head loss across the system exceeds the design pressure drop.